Copolymers of ω-bromoalkyl esters of acyclic unsaturated dicarboxylic acids

ABSTRACT

Copolymers are prepared from ω-bromoalkyl ester of acyclic unsaturated dicarboxylic acids and compounds copolymerizable therewith. The copolymers are useful as flame retardant plasticizers for polymers.

BACKGROUND OF THE INVENTION

This invention relates to novel copolymers wherein one of the monomersis an ω-bromoalkyl ester of an acyclic unsaturated dicarboxylic acid.

Further, this invention relates to plasticized polymer compositionscontaining said novel copolymers as flame retardant plasticizers.

Still further, this invention relates to novel plasticizer compositionscomprising a copolymer wherein one of the monomers is an ω-bromoalkylester of an acyclic unsaturated dicarboxylic acid.

SUMMARY OF THE INVENTION

In accordance with the present invention, there are provided flameretardant plasticizer compositions for natural and synthetic polymerswhich comprise a copolymer of an ω-bromoalkyl ester of an acyclicunsaturated dicarboxylic acid and a monomer copolymerizable therewith.The ω-bromoalkyl ester copolymers are characterized by the formula##STR1## wherein R is the incorporated residue, i.e., monomeric unitderived from the polymerization of an ethylenically unsaturatedcomonomer and n has a value of from about 10 to about 2,000,corresponding to a molecular weight distribution of from about 2,000 toabout 350,000

SPECIFIC EMBODIMENTS OF THE INVENTION

The novel copolymeric flame retardant plasticizers which are embodied bythe present invention are based on copolymers of an ω-bromoalkyl esterof an acyclic unsaturated dicarboxylic acid and a copolymerizablemonomer.

The ω-bromoalkyl esters utilized in the preparation of the novelcopolymers of the present invention are represented by the formula##STR2## wherein n represents 0 to 4; n' represents 0 to 4; x represents1 to 8; and x' represents 1 to 8. Preferably, x and x' are the same.

The ω-bromoalkyl esters are prepared by the reaction of the appropriateacid or acid anhydride with the appropriate brominated alcohol orequivalent.

Illustrative acids and acid anhydrides which are utilized to prepare theω-bromoalkyl esters include ethenedioic acid, propenedioic acid,butenedioic acid, pentenedioic acid, hexenedioic acid, octenedioic acid,nonendioic acid and decenedioic acid.

Illustrative ω-bromoalkyl esters of the described acids include thebis(bromomethyl)ester, the bis(2-bromoethyl) ester, thebis(3-bromopropyl)ester, the bis(4-bromobutyl)ester, thebis(5-bromoamyl)ester, the bis(6-bromohexyl)ester, thebis(7-bromoheptyl)ester, and the bis(8-bromooctyl)ester.

Representative ω-bromoalkyl esters of acyclic unsaturated acids whichare embodied by the present invention include bis(bromomethyl)ester ofethenedioic acid, bis(2-bromoethyl)ester of ethenedioic acid,bis(3-bromopropyl)ester of ethenedioic acid, bis(4-bromobutyl)ester ofethenedioic acid, bis(bromomethyl)ester of propenedioic acid,bis(5-bromoamyl) ester of propenedioic acid, bis(2-bromoethyl)ester ofbutenedioic acid, bis(4-bromobutyl)ester of butenedioic acid,bis(3-bromopropyl)ester of pentenedioic acid, bis(bromomethyl) ester ofpentenedioic acid, bis(6-bromohexyl)ester of hexenedioic acid,bis(4-bromobutyl)ester of hexenedioic acid, bis(bromometyl)ester ofheptenedioic acid, bis(7-bromoheptyl) ester of octenedioic acid,bis(2-bromoethyl)ester of nonenedioic acid, bis(3-bromopropyl)ester ofnonenedioic acid, bis(8-bromooctyl)ester of decenedioic acid, and thelike. Especially preferred as a coreactant with a copolymerizablemonomer is the bis(4-bromobutyl)ester of ethenedioic acid, i.e.,bis(4-bromobutyl)fumarate.

Brominated alcohols which are reacted with the abovedescribed acids toafford the ω-bromoalkyl esters which are utilized to prepare thecopolymers of the present invention include bromomethanol,2-bromoethanol, 3-bromopropanol, 4bromobutanol, 5-bromopentanol,6-bromohexanol, 7-bromoheptanol, and 8-bromooctanol. Additionally, theremay be used precursor materials which are converted in situ into theappropriate bromoalcohol. For instance, tetrahydrofuran is convertedinto 4-bromobutanol in the presence of hydrogen bromide. Other materialswhich may be used in lieu of the appropriate bromoalcohol are ethyleneoxide and 1,3-propylene oxide. Ethylene oxide is converted tobromoethanol and 1,3-propylene oxide is converted into 3-bromopropanolin the presence of HBr.

The ω-bromoalkyl esters described above are reacted with copolymerizableethylenically unsaturated monomers. Copolymerizable ethlenicallyunsaturated comonomers may be determined by reference to publishedcopolymerization reactivity ratios. The relation between the compositionof a monomer mixture and the copolymer formed from it is determined bythe monomer reactivity ratios of the particular monomer pair. An idealcopolymerization reaction is one wherein the reactivity value of onemonomer (r₁) times the reactivity of the second monomer (r₂) equals 1(i.e., r₁ r₂ =1). Since copolymerization only randomly would approachideal conditions, two monomers whose multiplied reactivity values equalless than one are considered to be copolymerizable.

The reactivity value of numerous polymerizable monomers has beenexperimentally determined (see CHEMICAL REVIEWS, Vol. 46, Mayo andWalling, pp. 212-222; and ENCYCLOPEDIA OF POLYMER SCIENCE ANDTECHNOLOGY, Vol. 4, pp. 193-222). From such reactivity values, adetermination may be made as to whether two monomers arecopolymerizable.

The reactivity value of ω-bromoalkyl esters has not been determined.Therefore, in order to determine possible monomers which wouldcopolymerize with the ω-bromoalkyl esters, e.g.,bis(4-bromobutyl)fumarate, it was decided to utilize the compoundclosest thereto for which the reactivity value had been found, and thusdetermine which monomers would copolymerize therewith in accordance withpublished reactivity values. Accordingly, diethyl fumarate was chosen asthe closest compound to the ω-bromoalkyl esters of the invention forwhich a reactivity value had been determined, and certain monomerscopolymerizable therewith were chosen in accordance with publishedvalues. The monomers initially chosen were diallyl phthalate, methylmethacrylate, N-vinyl pyrrolidone, allyl alcohol, acrylonitrile,acrylamide, ethyl acrylate, triallyl cyanurate and vinyl acetate. It wasbelieved that, since reactivity ratios indicated such monomers wouldcopolymerize with diethyl fumarate, they would also copolymerize withω-bromoalkyl esters such as bis(4-bromobutyl)fumarate. Subsequentexperiments proved that such monomers would, in fact, copolymerize withω-bromoalkyl esters such as bis(4-bromobutyl)fumarate. Accordingly, itis considered that any ethylenically unsaturated compound whosereactivity value multiplied by the reactivity value of diethyl fumarateis less than 1 would copolymerize with the described ω-bromoalkylesters. Accordingly, the following compounds are considered illustrativeof ethylenically unsaturated monomers which will copolymerize with thedesired ω-bromoalkyl esters: diallyl phthalate; alkyl methacrylates,e.g., methyl methacrylate; N-vinyl pyrrolidone; allyl alcohol,acrylonitrile; acrylamide; alkyl acrylates, e.g., ethyl acrylate;triallyl cyanurate; vinyl esters of lower acyclic carboxylic acids,e.g., vinyl acetate; conjugated diolefins, e.g., butadiene,2-chloro-1,3-butadiene; vinyl aromatics, e.g., styrene; vinyl chloride;vinylidene chloride, and the like. Preferred comonomers are triallylcyanurate, vinyl acetate and ethyl acrylate.

In general, the ω-bromoalkyl esters and comonomers are copolymerized byinitially heating a mixture of the appropriate ω-bromoalkyl ester and afree radical catalyst, such as t-butyl perbenzoate, azobisisobutyronitrile, or benzoyl peroxide, at a temperature of about 45° C.for approximately 1 hour. The temperature is then raised to 75° - 120°C. and comonomer is charged slowly and additional catalyst may be added.Continuous IR analysis indicates attainment of the desired degree ofcopolymerization.

The molar ratio of ω-bromoalkyl ester to comonomer in the reactionmixture is, generally, from about 1:1 to about 20:1. Preferably, theratio is from about 2:1 to about 7:1.

The copolymer flame retardant plasticizers described above may be usedas the sole plasticizer in polymer formulations but may also be used inconjunction with conventional plasticizers, such as the widely usedphthalate and phosphate plasticizers. Thus, the fire retardantplasticizers described may be used in combination with phosphate esterssuch as trialkyl phosphates, dialkylaryl phosphates, alkyldiarylphosphates and triaryl phosphates, e.g., tributyl phosphate, trioctylphosphate, and trialkyl phosphate prepared from mixtures of C₇ - C₉ -C₁₁ alcohols, dioctylphenyl phosphate, diisodecylphenyl phosphate,isopropylphenyl diphenyl phosphate, octyldiphenyl phosphate,t-butylphenyl diphenyl phosphate, isodecyl diphenyl phosphate,cumylphenyl diphenyl phosphate, triphenyl phosphate, cresyl diphenylphosphate, tricresyl phosphate and the like. Similarly, conventionalphthalate plasticizers may be used in the polymer compositions describedin the present invention, e.g., dialkyl phthalates wherein the alkylportion of the ester radical contains from 2 to 11 carbon atoms, i.e.,from mixtures of C₇ - C₉ - C₁₁ alcohols. Further, mixed phthalate esterscontaining an alkyl ester portion and an aryl ester portion arecontemplated, e.g., butylbenzyl phthalate and similar materials. Theflame retardant plasticizers of the present invention, whether alone orin combination with conventional plasticizers, are normally incorporatedinto polymer systems which may contain other conventional formulatingadditives such as fillers, stabilizers, colorants, antioxidants, foamingagents and the like.

Depending upon the particular polymer plasticized and the specificcopolymer plasticizer utilized, and also depending on whether suchplasticizer is used along or in conjunction with conventionalplasticizers, the flame retardant plasticizers of this invention may beincorporated at various concentrations. In general, the copolymerplasticizers described are utilized at concentrations of from about 1 toabout 100 phr (i.e., parts per hundred parts of resin), preferably fromabout 10 to about 40 phr.

The following examples illustrate specific, nonlimiting embodiments ofthe invention.

In the following examples, certain tests are made, certain terms areused and comparisons are made on the basis of those tests. Accordingly,the following definitions will serve as the basis of an understanding ofthe tests utilized in the examples:

1. "Oxygen Index" -- this test uses the procedure of ASTM-D2863-74 whichemploys a vertical glass tube 60 cm. high and 8.4 cm. in diameter, inwhich a rod or strip specimen 8 cm. long is held vertically by a clampat its bottom end. A mixture of oxygen with another gas or gases,usually nitrogen, is metered into the bottom of the tube, passingthrough a porous metal plate at the bottom to smooth the flow of gas.The sample is ignited at its upper end by a methane flame which is thenwithdrawn, and the atmosphere that permits steady burning down of thespecimen is determined. The limiting oxygen index is the minimumfraction of oxygen in an oxygen-nitrogen mixture which will just permitthe sample to burn. The results are shown as the minimum concentrationof oxygen, expressed as volume percent, which will just supportcombustion. The higher the oxygen index, the less flammable is thematerial.

2. "UL-94" test is utilized to determine the resistance of a plasticmaterial to continued combustion and to ignition. In this test, astandard specimen is supported from the upper 6.4 mm. of the specimen,with the longitudinal access vertical, by a clamp on a ring stand sothat the lower end of the specimen is 9.5 mm. above the top of theburner tube and 305 mm. above a horizontal layer of dry absorbantsurgical cotton. The burner is placed remote from the specimen, ignitedand adjusted to produce a blue flame 19 mm. high. The test flame isplaced centrally under the lower end of the test specimen and allowed toremain for 10 seconds. The test flame is then withdrawn and the durationof the flaming of the specimen noted. When the flaming of the specimenceases, the test flame is immediately placed again under the specimen.After 10 seconds, the test flame is again withdrawn and the duration offlaming and glowing noted.

In this procedure, V-0 is the highest rating obtainable. It indicates anaverage burn time of less than 50 seconds (2 ignitions for each of 5specimens), no one burn of greater than 10 seconds, no dripping flameand no afterglow beyond 30 seconds after the second removal of theflame. A rating of V-1 allows up to 250 seconds average burn time and aV-2 rating indicates the sample drips and flames.

EXAMPLE I

This example illustrates the preparation of bis(4-bromobutyl)fumarate.In place of 4-bromobutanol, there was used tetrahydrofuran which isconverted to 4-bromobutanol in situ by HBr.

To a 1-liter reactor, equipped with thermometer and condenser, therewere added 99.6 g. (1.02 moles) maleic anhydride, 162 g. (2.25 moles)tetrahydrofuran and 4 g. p-toluenesulfonic acid. Hydrogen bromide (177.4g., 2.19 moles) was added substrate over a period of 1.75 hours whilethe temperature was held at approximately 70° C.

Benzene (40 g.) was then added and the mixture was heated to reflux(approximately 95° C.) and water of esterification was removed asformed, during which time the reaction temperature rose to approximately130° C.

The reaction mixture was cooled and the pH adjusted to 9.0 by additionof aqueous sodium carbonate.

Separation of bis(4-bromobutyl)fumarate and refining afforded a yield of378 g. Due to the time required for complete reaction (1.75 hours forHBr addition and 4 hours heatup and reflux) and the acid pH of thereaction mixture, maleate compounds formed were isomerized to thefurmarate form.

In the same manner, other ω-bromoalkyl esters may be prepared byreacting the appropriate anhydride with the appropriate bromoalkanol.

Thus, the following esters may be prepared:

bis(bromomethyl)fumarate

bis(2-bromoethyl)fumarate

bis(3-bromopropyl)fumarate

bis(5-bromopentyl)fumarate

bis(6-bromohexyl)fumarate

bis(7-bromoheptyl)fumarate

bis(8-bromooctyl)fumarate

bis(2-bromoethyl)ester of propenedioic acid

bis(4-bromobutyl)ester of butenedioic acid

bis(5-bromopentyl)ester of decenedioic acid

EXAMPLE II

This example illustrates the preparation of a copolymer ofbis(4-bromobutyl)fumarate and triallyl cyanurate.

To a 500 ml. flask, equipped with agitator, thermometer, dropping funneland gas inlet tube, there were charged 98.2 g.bis(4-bromobutyl)fumarate. Heat was applied to raise the temperature toabout 45° C., agitation was begun and 1 g. t-butyl perbenzoate wasadded. The temperature was then raised to approximately 110° C. Afterone hour, 1.9 g. triallyl cyanurate was added over a 1 hour period.After addition of the comonomer, reaction temperature was held atapproximately 110° C. until IR analysis indicated the desired degree ofcopolymerization was obtained. Yield of copolymer was 98.93 g.

Continuous IR analyses are conducted during the course of thecopolymerization, as are viscosity determinations. Generally, thecopolymerization reaction is terminated when the degree of conversion,as measured by viscosity, is such that the product is a free-flowingviscous liquid at 25° C.

In the same fashion, preparation of the following copolymers arecontemplated:

bis(bromomethyl)fumarate/styrene

bis(2-bromoethyl)fumarate/diallyl phthalate

bis(3-bromopropyl)fumarate/methyl methacrylate

bis(4-bromobutyl)fumarate/acrylonitrile

bis(5-bromopentyl)fumarate/N-vinyl pyrrolidone

bis(6-bromohexyl)fumarate/allyl alcohol

bis(7-bromoheptyl)fumarate/acrylamide

bis(8-bromooctyl)fumarate/vinyl acetate

bis(4-bromobutyl)ester of butenedioic acid/ethyl acrylate

bis(2-bromoethyl)ester of hexenedioic acid/triallyl cyanurate

bis(3-bromopropyl)ester of octenedioic acid/vinyl acetate

bis(5-bromopentyl)ester of decenedioic acid/triallyl cyanurate

EXAMPLE III

This example illustrates the preparation of a copolymer ofbis(4-bromobutyl)fumarate and vinyl acetate.

To a 500 ml. flask, equipped with agitator, thermometer, droppingfunnel, gas inlet tube and condenser, were charged 250 g. (0.647 mole)bis(4-bromobutyl)fumarate under nitrogen atmosphere. The temperature wasraised to 45° C. at which time the agitator was turned on and 1 g. ofbenzoyl peroxide was added. The reaction mixture was then heated toapproximately 80° C. and held for one hour. Addition of 8.9 g. vinylacetate was started and continued over 2.5 hours. The reaction mass wasthen held at a temperature of approximately 80° C. until IR analysisindicated that the desired degree of copolymerization reaction wasobtained. There was afforded 235 g. of a copolymer ofbis(4-bromobutyl)fumarate and vinyl acetate.

In the same fashion, preparation of the following copolymers iscontemplated:

bis(bromomethyl)ester of propenedioic acid/vinyl acetate

bis(2-bromoethyl)ester of propenedioic acid/methyl methacrylate

bis(2-bromoethyl)ester of butenedioic acid/butyl methacrylate

bis(4-bromobutyl)ester of butenedioic acid/propyl acrylate

bis(4-bromobutyl)ester of pentenedioic acid/vinyl fumarate

bis(bromomethyl)ester of hexenedioic acid/butadiene

bis(4-bromobutyl)fumarate/3-chlorobutadiene-1,3

bis(4-bromobutyl)fumarate/styrene

bis(4-bromobutyl)fumarate/viny chloride

EXAMPLE IV

This example illustrates the preparation of a copolymer ofbis(4-bromobutyl)fumarate and ethyl acrylate.

To a 500 ml. flask, equipped with agitator, thermometer, dropping funneland condenser, were charged 167.6 g. bis(4-bromobutyl)fumarate undernitrogen atmosphere. The temperature was raised to approximately 60° C.and 3.95 g. benzoyl peroxide was added during agitation. The reactionmixture temperature was raised to about 80° C. over one hour anddropwise addition was begun of a solution of 30 g. ethyl acrylate in 30g. benzene. Addition of ethyl acrylate was complete after about 3 hours.The reaction mixture was then held at a temperature of approximately 80°C. until IR analysis indicated that the desired degree ofcopolymerization was obtained. There was afforded 180.8 g. of acopolymer of bis(4-bromobutyl)fumarate and ethyl acrylate.

EXAMPLE V

This example illustrates the effectiveness of a copolymer ofbis(4-bromobutyl)fumarate and vinyl acetate as a flame retardantplasticizer for polyethylene.

Polyethylene (55 g.) was processed in a Brabender mixing head at 180° C.until fused. There was then prepared an 0.32 cm. thick molded sheetwhich was 12.7 × 12.7 cm. The sheet was then tested for oxygen index inaccordance with the procedure of ASTM-D2863-74. The polyethylene had anoxygen index of 19.1. A replicate sample of polyethylene was preparedcontaining 13.75 parts of the bis(4-bromobutyl)fumarate/vinyl acetatecopolymer of Example III. Testing of the sample containing the copolymerplasticizer showed that the sample had an oxygen index of 23.1. Thepolyethylene used was Monsanto 6003 high density polyethylene.

It is contemplated that similar results would be afforded byincorporating the described flame retardant plasticizer inpolypropylene, vinyl halide polymers such as polyvinyl chloride andvinyl chloride copolymers, polymerized esters of acrylic and methacrylicacids, polymerized esters of carbonic acid, acrylonitrile polymers,diolefin polymers such as polybutadiene, polychloroprene, andpolyisoprene, and butyl rubbers.

EXAMPLE VI

This example illustrates the effectiveness of a copolymer ofbis(4-bromobutyl)fumarate and triallyl cyanurate as a flame retardantplasticizer for polystyrene (Monsanto LUSTREX high impact polystyrene).

Standard UL-94 specimens were prepared and subjected to the UL-94vertical burn test to characterize ignition and combustion. Each of fivespecimens contained 15% by weight copolymer ofbis(4-bromobutyl)fumarate/triallyl cyanurate.

Subjection of the specimens to the test conditions of UL-94 afforded arating of V-0. The average burn time of the five specimens, with twoignitions each, was 3.7 seconds. Replicate control samples, notcontaining the described copolymer, burned.

It is contemplated that similar results would be obtained byincorporating the described flame retardant plasticizer in polyesters,polyurethanes, phenolics, aminoplasts and polyamides.

The flame retardant plasticizer compounds of the present invention areuseful as flame retardants for a wide variety of natural and syntheticpolymer materials.

Synthetic polymer materials, i.e., those high molecular weight organicmaterials which are not found in nature, with which the compounds of theinvention are advantageously employed may be either linear orcrosslinked polymers and may be in the form of sheets, coatings, foamsand the like. They may be either those which are produced by addition orcondensation polymerization.

An important class of polymers which are beneficially flame retardedwith the compounds of the invention are those obtained from apolymerizable monomer compound having ethylenic unsaturation. Aparticularly preferred class of polymers which are flame retardedconsist of the polymerized vinyl and vinylidene compounds, i.e., thosehaving the CH₂ ═ C< radical. Compounds having such a radical are, forexample, the solid polymeric alkenes, such as polyethylene,polypropylene, polyisobutylene or ethylene/propylene copolymers;polymerized acrylyl and alkacrylyl compounds such as acrylic,fluoroacrylic and methacrylic acids, anhydrides, esters, nitriles andamides, for example, acrylonitrile, ethyl or butyl acrylate, methyl orethyl methacrylate, methoxymethyl or 2-(2-butoxyethoxy)ethylmethacrylate, 2-(cyanoethoxy)ethyl or 3-(3-cyanopropoxy)propyl acrylateor methacrylate, 2(diethylamino)ethyl or 2-chloroethyl acrylate ormethacrylate, acrylic anhydride or methacrylic anhydride; methacrylamideor chloroacrylamide; ethyl or butyl chloroacrylate; the olefinicaldehydes such as acrolein, methacrolein and their acetals; the vinyland vinylidene halides such as vinyl chloride, vinyl fluoride,vinylidene fluoride and 1-chloro-1-fluoroethylene; polyvinyl alcohol;the vinyl carboxylates such as vinyl acetae, vinyl chloroacetate, vinylpropionate, and vinyl 2-ethyl-hexanoate; the N-vinyl imides such asN-vinyl phthalimide and N-vinyl succinamide; the N-vinyl lactams such asN-vinyl caprolactam and N-vinyl butyrolactam; vinyl aromatic hydrocarboncompounds such as styrene, alpha-methylstyrene, 2,4-dichlorostyrene,alpha- or beta-vinylnaphthalene, divinyl benzene and vinyl fluorene; thevinyl ethers such as ethyl vinyl ether or isobutyl vinyl ether;vinyl-substituted heterocyclic compounds such as vinyl pyridine, vinylpyrrolidone, vinylfuran or vinylthiophene; the vinyl or vinylideneketones such as methyl vinyl ketone or isopropenyl ethyl ketone;vinylidene cyanide. Homopolymers of the above compounds or copolymersand terpolymers thereof are beneficially flame retarded by the compoundsof the present invention. Examples of such copolymers or terpolymers arethose obtained by polymerization of the following monomer mixtures:vinyl chloride/vinyl acetate; ethylene/vinyl chloride/vinyl acetate,acrylonitrile/vinyl pyridine, styrene/methyl methacrylate,styrene/N-vinyl pyrrolidone, cyclohexyl methacrylate/vinylchloroacetate, acrylonitrile/vinylidene cyanide, methylmethacrylate/vinyl acetate, ethyl acrylate/methacrylamide/ethylchloroacrylate, vinyl chloride/vinylidene chloride/vinyl acetate.

Other polymers of compounds having the ethylenic group, >C ═ C<, arehomopolymers, copolymers and terpolymers of the alpha-, beta-olefinicdicarboxylic acids and derivatives thereof such as the anhydrides,esters, amides, nitriles and imides, for example, methyl, butyl,2-ethylhexyl or dodecyl fumarate or maleate; maleic, chloromaleic,citraconic or itaconic anhydride; fumaronitrile, dichlorofumaronitrileor citracononitrile; fumaramide, maleamide or N-phenyl maleamide.Examples of particularly useful polymers and terpolymers prepared fromthe alpha-, beta-olefinic dicarboxylic compounds are the copolymers ofmaleic anhydride and a vinyl compound such as ethylene, propylene,isobutylene, styrene, alpha methylstyrene, vinyl acetate, vinylpropionate, methyl isopropenyl ketone, isobutyl vinyl ether, thecopolymers of dialkyl fumarate such as ethyl or butyl fumarate and vinylcompounds such as styrene, vinyl acetate, vinylidene chloride, ethylmethacrylate, acrylonitrile and the like.

The compounds of the invention act as flame retardant plasticizers forthe polymers and copolymers of unsaturated, cyclic esters of carbonicacid, for example, homopolymeric vinylene carbonate or the copolymers ofvinylene carbonate with ethylenic compounds such as ethylene, vinylchloride, vinyl acetate, 1,3-butadiene, acrylonitrile,methacrylonitrile, or the esters of methacrylic or acrylic acid.

Readily flame retarded by the compounds of the invention are thepolyarylcarbonate polymers such as the linear polyarylcarbonates formedfrom diphenols or dihydroxy aromatic compounds including single andfused-ring nuclei with two hydroxy groups as well asmonohydroxy-substituted aromatic residues joined in pairs by variousconnecting linkages. Examples of the foregoing include dihydroxybenzenes, naphthalenes and the like, the dihydroxydiphenyl ethers,sulfones, alkanes, ketones and the like.

The compounds of the invention also act as flame retardants forpolymers, copolymers or terpolymers of polymerizable compounds having aplurality of double bonds, for example, rubbery, conjugated dienepolymerizates such as homopolymerized 3-butadiene, 2-chlorobutadiene orisoprene and linear copolymers or terpolymers such asbutadiene/acrylonitrile, isobutylene/butadiene, butadiene/styrene;esters of saturated di- or poly-hydroxy compounds with olefiniccarboxylic acids such as ethylene glycol dimethacrylate, triethyleneglycol dicrotonate or glyceryl triacrylate; esters of olefinic alcoholswith dicarboxylic acids or with olefinic monocarboxylic acids such asdiallyl adipate, divinyl succinate, diallyl fumarate, allyl methacrylateor crotyl acrylate and other diethylenically unsaturated compounds suchas diallyl carbonate, divinyl ether or divinylbenzene, as well as thecrosslinked polymeric materials such as methyl methacrylate/diallylmethacrylate copolymer or butadiene/styrene/divinyl benzene terpolymer.

The cellulose derivatives are flame retarded by the compounds of thepresent invention. For example, cellulose esters such as celluloseacetate, cellulose triacetate or cellulose butyrate, the celluloseethers such as methyl or ethyl cellulose, cellulose nitrate,carboxymethyl cellulose, cellophane, rayon regenerated rayon and thelike may be flame retarded.

The compounds of the present invention are well suited for flameretarding liquid resin compositions of the polyester type, for example,the linear polyesters which are obtained by the reaction of one or morepolyhydric alcohols with one or more alpha-, beta-unsaturatedpolycarboxylic acids alone or in combination with one or more saturatedpolycarboxylic acid compounds, or the crosslinked polyester resins whichare obtained by reacting a linear polyester with a compound containing aCH₂ ═ C< group.

The compounds of the present invention are compatible flame retardantsfor epoxy resins. Such resins are condensation products formed by thereaction of a polyhydroxy compound and epichlorohydrin, whichcondensation products are subsequently cured by the addition ofcrosslinking agents. The hydroxy compounds may be, for example, ethyleneglycol, 4,4'-isopropylidenediphenol and similar materials. Thecrosslinking agent employed in the curing step may be a dicarboxyliccompound such as phthalic anhydride or adipic acid, but is moregenerally a polyamine such as ethylene, diamine, paraphenylamine diamineor diethylene triamine.

Polyurethanes are a class of polymer materials which are flame retardedby the compounds of the present invention. The polyurethanes, like theabove-mentioned polyesters, are materials which are employed instructural applications, for example, as insulating foams, in themanufacture of textile fibers, as resin bases in the manufacture ofcurable coating compositions and as impregnating adhesives in thefabrication of laminates of wood and other fibrous materials.Essentially, the polyurethanes are condensation products of adiisocyanate and a compound having a molecular weight of at least 500and preferably about 1,500 - 5,000, and at least two reactive hydrogenions. The useful active hydrogen-containing compounds may be polyestersprepared from polycarboxylic acids and polyhydric alcohols, polyhydricpolyalkylene ethers having at least two hydroxy groups, polythioetherglycols, polyesteramides and similar materials.

The polyesters or polyester amides used for the production of thepolyurethane may be branched and/or linear, for example, the esters ofadipic, sebacic, 6-aminocaproic, phthalic, isophthalic, terephthalic,oxalic, malonic, succinic, maleic, cyclohexane-1,2-dicarboxylic,cyclohexane-1,4-dicarboxylic, polyacrylic, naphthalene-1,2-dicarboxylic,fumaric or itaconic acids with polyalcohols such as ethylene glycol,diethylene glycol, pentaglycol, glycerol, sorbitol, triethanolamineand/or amino alcohols such as ethanolamine, 3-aminopropanol, and withmixtures of the above polyalcohols and amines.

The alkylene glycols and polyoxyalkylene or polythioalkylene glycolsused in the production of polyurethanes may be ethylene glycol,propylene glycol, butylene glycol, diethylene glycol, triethyleneglycol, polythioethylene glycol, dipropylene glycol and the like.

Generally, any of the polyesters, polyisocyanatemodified polyesters,polyester amides, polyisocyanate-modified polyester-amides, alkyleneglycols, polyisocyanate-modified alkylene glycols, polyoxyalkyleneglycols and polyisocyanatemodified polyoxyalkylene glycols having threereactive hydrogen atoms, three reactive carboxylic and/or especiallyhydroxyl groups may be employed in the production of polyurethanes.Moreover, any organic compound containing at least two radicals selectedfrom the group consisting of hydroxy and carboxy groups may be employed.

The organic polyisocyanates useful for the production of polyurethanesinclude ethylene diisocyanate, ethylidene diisocyanate,propylene-1,2-diisocyanate, m-phenylene diisocyanate, 2,4-tolylenediisocyanate, triphenylmethane triisocyanate, or polyisocyanates inblocked or inactive form such as the bis-phenyl carbamates of tolylenediisocyanate and the like.

Phenolic resins are flame retarded by the compounds of the presentinvention, which compounds may be incorporated into the phenolic resineither by milling and molding applications or by addition tofilm-forming or impregnating and bonding solutions prior to casting.Phenolic resins with which the present compounds are employed are, forexample, the phenol-aldehyde resins prepared from phenols such asphenol, cresol, xylenol, resorcinol, 4-butylphenyl, cumylphenol,4-phenylphenol, nonylphenol, and aldehydes such as formaldehyde,acetaldehyde or butyraldehyde in the presence of either acetic or basiccatalysts, depending upon whether the resin is intended for use as amolding or extruding resin or as the resin base in coating andimpregnating compositions.

Aminoplasts are another group of aldehyde resins which are flameretarded by the compounds of the invention. Examples of aminoplasts arethe heat-convertible condensation products of an aldehyde with urea,thiourea, guanidine, cyanamide, dicyandiamide, alkyl or aryl guanaminesand the triazines such as melamine, 2-fluoro-4,6-diamine-1,3,5-triazineand the like. When the aminoplasts are to be used as impregnatingagents, bonding adhesives, coatings and in casting of films, thecompounds of the present invention are incorporated into solutions orsuspensions in which the aminoplast is carried. The resulting mixturesgive strong, fireretardant laminates when sheets of paper, glass, clothor fabric are impregnated therewith and cured.

Another class of compounds which are flame retarded by the compounds ofthe present invention are the nylons, for example, the superpolyamideswhich are generally obtained by the condensation of a diamine, forexample, hexamethylene diamine with a dicarboxylic acid, for example,adipic acid.

Other polyamides which are flame retarded in accordance with the presentinvention are the polypeptides which may be prepared, for example, byreaction of N-carbobenzyl oxyglycine with glycine or mixtures of glycineand lysine or an N-carboxy amino acid anhydride such asN-carboxy-DL-phenylalanine anhydride, piperidone,2-oxohexamethyleneimine and other cyclic amides. The compounds of thepresent invention can be incorporated into molding or extrudingcompositions for a flame retardant effect.

The compounds of the present invention are also useful as flameretardants for linear polymers obtained by the selfcondensation ofbifunctional compounds, for example, the polyethers which are derived bythe self-condensation of dihydric alcohols such as ethylene glycol,propylene glycol or hexamethylene glycol; the polyesters which areobtained by the self-condensation of hydroxy acids such as lactic acidor 4-hydroxybutyric acid; the polyamides which are prepared by theself-condensation of aminocarboxylic acids such as 4-aminobutyric acid;the polyanhydrides which are formed by the self-condensation ofdicarboxylic acids such as sebacic or adipic acid.

The preferred synthetic polymer materials which are flame retarded bythe compounds of the present invention are the vinyl halide polymers inthe form of milled products, plastisols and foams, polystyrene,polyolefins, e.g., polyethylene, rigid and flexible polyurethanecoatings and foams, epoxy resins, and GRS rubbers. The vinyl halidepolymers can be simple homopolymers of vinyl chloride or vinylidenechloride, such as polyvinyl chloride or polyvinylidene chloride, orcopolymers or terpolymers in which the essential polymeric structure ofpolyvinyl chloride is interspersed at intervals with residues of otherethylenically unsaturated compounds copolymerizable therewith. Theessential properties of the polymeric structure of polyvinyl chloride isretained if not more than about 40 percent of a comonomer iscopolymerized therewith. Especially preferred copolymers includeethylene/vinyl chloride and vinyl chloride/acrylonitrile copolymers.Especially preferred terpolymers include ethylene/vinylchloride/acrylonitrile, ethylene/vinyl chloride/acrylic acid andethylene/vinyl chloride/acrylamide terpolymers.

Natural polymeric materials which may be flame retarded by the compoundsof the present invention include natural rubber, cellulose esters, forexample, cellulose acetate and cellulose nitrate, ethyl cellulose, corkand wood flour products and similar cellulosic materials.

The polymer formulations which are flame retarded in accordance with thepresent invention, whether in sheet or film form or of foam or moldedstructure, may contain various conventional additives such as fillers,extenders, crosslinking agents and colorants. Minor amounts ofstabilizers, for example, are usually incorporated to reduce the effectsof heat and light.

When foamable compositions are used, the composition may be aself-blowing polymer or the polymer may be blown by chemical ormechanical means or by the use of compressed gas. Fillers which arefrequently employed to lower the cost of the finished material and tomodify its properties include calcium carbonate and magnesium silicate.When fillers are employed, they are generally present in an amount of upto about 150 parts by weight of filler per 100 parts by weight ofpolymer formulation.

Where a colored or tinted composition is desired, colorants orcolor-pigments are incorporated in amounts of from about one to aboutfive parts by weight to 100 parts by weight of polymer.

Surfactants such as silicones are normally added to foam formulationswhich are mechanically frothed. The surfactants reduce the surfacetension of the foam and thereby increase the air or gas entrapmentcharacteristics of the foam.

Additionally, glass forming inorganic materials such as zinc borate,zinc oxide, lead oxide, lead silicate and silicon dioxide may be addedto decrease the flame and smoke generating characteristics of thepolymer.

Additionally, the flame retardant plasticizers may be utilized inconjunction with the oxides, hydroxides, hydrates or salts of metalssuch as aluminum, magnesium, calcium, antimony, vanadium, chromium,molybdenum, tungsten, manganese, iron, cobalt, nickel, palladium,platinum, copper, zinc, mercury, germanium, tin and lead.

The ω-bromoalkyl esters of the invention may also be combined, eitheralone or in admixture with the described metal compounds, with otherflame retardant and smoke retardant materials and char-formingmaterials, such as with ethylene/maleic anhydride adducts and complexesor salts thereof, with metals and metal salts such as iron, antimony,tin, zinc and copper, with adducts of furan and maleic anhydride andbrominated derivatives thereof. Also, ω-bromoalkyl esters ofmonocarboxylic acids may be combined with the esters of the presentinvention.

We claim:
 1. Copolymer of the formula ##STR3## wherein R is themonomeric unit derived from the polymerization of an ethylenicallyunsaturated comonomer the reactivity value of which, when multiplied bythe reactivity value of diethyl fumarate, is less than one and n has avalue of from about 10 to about 2,000.
 2. Copolymer of claim 1 whereinsaid alkyl is butyl.
 3. Copolymer of claim 1 wherein said comonomer istriallyl cyanurate.
 4. Copolymer of claim 1 wherein said comonomer isvinyl acetate.
 5. Copolymer of claim 1 wherein said comonomer is ethylacrylate.
 6. Copolymer of bis(4-bromobutyl)fumarate and triallylcyanurate.
 7. Copolymer of bis(4-bromobutyl)fumarate and vinyl acetate.8. Copolymer of bis(4-bromobutyl)fumarate and ethyl acrylate.